mr ,i think this was on an old post last year,didn't they change the spindles to a new and better type? a3/4 inch shaft isn't to heavy.the blades that came on the mower are differnt than the one pt sold me when i picked it up. they are too big and hit the sides of the deck when you have heavy grass.the new ones have a bushing that you have to use,and they are a lot heaver and they work fine.they at pt do have commercial decks but i don't think for the 400 series.